Attachment patch for mounting an electronic monitoring device to the inside of a pneumatic tire

ABSTRACT

A patch and method for mounting an electronic monitoring device to the innerliner of a pneumatic tire is provided wherein the monitoring device is potted directly to an attachment patch. A frame is built on an attachment patch and the electronic monitoring device is disposed inside the frame. An encapsulation material is poured into the frame and cured to encapsulate the monitoring device directly against the patch. The patch may then be connected to the innerliner of a pneumatic tire.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of U.S. application Ser. No.09/539,856 filed Mar. 31, 2000; the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention generally relates to a patch for mountingan electronic monitoring device to the inside surface of a pneumatictire. More particularly, the present invention relates to a patch havingan electronic monitoring device encapsulated directly to the patch sothat it may be mounted to a tire with the patch.

[0004] 2. Background Information

[0005] Monitoring the internal conditions of a pneumatic tire while thetire is in use on a vehicle is becoming increasingly desired in the art.One problem with this technology is protecting the relatively sensitiveelectronic monitoring device in the relatively harsh environment insidea tire. Another problem in the art is that the inner surface of a tiredoes not have surfaces where monitoring devices may be easily mounted ina secure manner.

[0006] Protecting monitoring devices against harsh tire conditions hasbeen accomplished in the past by encapsulating the monitoring device inan encapsulation or potting material. The potting material is pouredover the monitoring device and fills the voids around the elements ofthe monitoring device. The material hardens and forms a protective blockhaving a high modulus of elasticity around the elements of themonitoring device. The monitoring device is protected in this mannerfrom the flexing and shock forces experienced in a pneumatic tire.

[0007] Rubber patches are also known in the art to mount monitoringdevices to the inner surface of a tire. The potted monitoring device hasbeen connected to the patch with adhesive and the patch was then adheredto the innerliner of the tire. Other methods of mounting monitoringdevices inside tires include forming a pocket in the tire and placingthe monitoring device in the pocket. Other methods have placed a rubberpatch over the top of the monitoring device to hold the monitoringdevice against the tire sidewall.

[0008] One problem with these mounting solutions is the relatively highnumber of steps required to mount the monitoring device to the tire.Another problem is the number of times the monitoring device must behandled prior to mounting inside the tire. More importantly, the usersof the monitoring devices desire stronger connections between themonitoring device and the tire.

[0009] Another problem in the art occurs when the antenna is mounted ina different substraight than the monitoring device. In these situations,a connection must be formed between the monitoring device and theantenna. An example of this situation is shown in patent applicationSer. No. 09/301,781 filed Apr. 29, 1999, which is owned by the Assigneeof the present application. In this situation, a pair of connectors areused to form the direct physical connection between the antenna and themonitoring device. The problem that has occurred is that the adhesiveused to bond the monitoring device to the patch is forced around theconnectors sometimes flowing into the connectors. The art desires asolution to this problem by providing a method of connecting theencapsulated monitoring device to a patch while not fouling theconnectors.

SUMMARY OF THE INVENTION

[0010] In view of the foregoing, the present invention provides amounted electronic monitoring device ready for mounting to the inside ofthe tire. The invention solves the problems in the art by directlypotting the monitoring device to a rubber attachment patch to form anassembly.

[0011] The assembly of the present invention includes a rubber patchhaving a first surface and a second surface. An electronic monitoringdevice is positioned adjacent the first surface of the patch with anencapsulation material surrounding at least a portion of the electronicmonitoring device. The encapsulation material bonds with the patch toconnect the encapsulated monitoring device to the patch.

[0012] Another aspect of the invention preferably provides placing theconnecting elements used to electrically connect the monitoring deviceto an antenna embedded within the patch in a location where theconnecting elements are surrounded by the encapsulation material.

[0013] Another aspect of the invention provides a method for creatingthe assembly wherein the number of handling steps and fabricating stepsare minimized.

[0014] The method of the present invention includes the steps ofproviding a patch having a first surface and a second surface, providingan electronic monitoring device adjacent the first surface of the patch,and encapsulating the electronic monitoring device directly to the firstsurface of the patch.

[0015] An advantage of the invention is that the patch provides a securemounting platform for the monitoring device that can be readily attachedto the innerliner of a pneumatic tire.

[0016] Another advantage of the invention is that the connection betweenthe encapsulated monitoring device and the attachment patch does notrely on the strength of an adhesive to connect two separately formedelements.

[0017] Another advantage of the invention is that the assembly protectsthe connections between the antenna and the monitoring device.

[0018] Another advantage of the invention is that the connectionsbetween the monitoring device and the antenna do not become fouled byadhesive because the antenna and monitoring device are connected beforethe encapsulation material is poured into the mold.

[0019] The foregoing advantages, construction, and operation of thepresent invention will become more readily apparent from the followingdescription and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the invention, illustrative of thebest mode in which applicant contemplated applying the principles of theinvention, are set forth in the following description and are shown inthe drawings and are particularly and distinctly pointed out and setforth in the appended Claims.

[0021]FIG. 1 is a sectional view of a pneumatic tire with anencapsulated monitoring device mounted to the innerliner of the tirewith an attachment patch;

[0022]FIG. 2 is a perspective view of the attachment patch with apotting frame assembled and placed on the upper surface of theattachment patch to surround the connectors for the antenna;

[0023]FIG. 3 is a top plan view of FIG. 2;

[0024]FIG. 4 is a sectional side view of the attachment patch and thepotting frame with the electronic monitoring device positioned withinthe potting frame and the potting material being poured into the pottingframe;

[0025]FIG. 4A is a view similar to FIG. 4 showing an alternativeembodiment of the invention where the potting frame is held against theattachment patch with pressure;

[0026]FIG. 5 is a view similar to FIG. 4 showing the potting framesubstantially filled with the potting material; and

[0027]FIG. 6 is a view similar to FIG. 4 showing one embodiment of thefinal product.

[0028] Similar numbers refer to similar parts throughout thespecification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] An assembly used to mount an electronic monitoring device to theinside surface of a pneumatic tire is indicated generally by the numeral10 in the drawings. Assembly 10 preferably mounts the electronicmonitoring device to the innerliner 12 of a pneumatic tire 14 so thatthe electronic monitoring device may monitor at least one engineeringcondition of tire 14.

[0030] Assembly 10 generally includes an attachment patch 20 and anencapsulated monitoring device 22. Attachment patch 20 is used toconnect encapsulated monitoring device 22 to innerliner 12 so that themonitoring device may perform its measurements. Attachment patch 20includes a first side 24 configured to receive encapsulated monitoringdevice 22 and a second side 26 configured to attach to tire 14.Attachment patch 20 is preferably fabricated from rubber. The rubbermaterial is preferably vulcanized at a pre-selected temperature and atime sufficient to vulcanize the patch. The patch may be fabricated froma rubber selected from the group consisting of Ethylene Propylene DieneMonomer (EPDM) rubber, butyl rubber, natural rubber, neoprene, andmixtures thereof. One preferred embodiment is a mixture of chlorobutylrubber and natural rubber. Another preferred embodiment is bromobutylrubber. Another embodiment is a mixture of Styrene-Butadiene rubber(SBR) natural rubber. Typically, patches made from these rubbercompositions may be cured by heating to a temperature of about 150degrees Celsius and holding this temperature for about thirty minutes.The time and temperature may be modified as necessary to achievesufficient curing of the patch for further manufacturing steps. Thepresent invention also contemplates that patch 20 may be fabricated froma variety of other rubber mixtures known in the art. In addition torubbers, patch 20 may be fabricated from other materials that may beadhered to tire 14 and accept encapsulated monitoring device 22 asdescribed below. Thermoplastic Elastomers, Thermoplastic Urethanes orThermoplastic Olefins may also be used to form attachment patch 20.

[0031] In one embodiment of the present invention, patch 20 carries anantenna 30 used to send and receive signals from encapsulatingmonitoring device 22. Antenna 30 includes connecting elements 32 thatprotrude outwardly from the outer perimeter of patch 20. Connectingelements 32 may be the male or female portion of a pin and socket-typeconnector. Connecting elements 32 are used to allow a monitoring package34 to be plugged into antenna 30 after antenna 30 is cured into to patch20. Antenna 30 may be connected to patch 20 in a variety of other waysother than being cured into patch 20. For instance, antenna 30 may bemounted on an outer surface of patch 20. Monitoring package 34 mayinclude the various sensors, controllers, memory devices, and powersupplies necessary to perform the monitoring, transmitting, andreceiving functions desired in the art. Monitoring package 34 must beconnected to antenna 30 so that it may communicate with a data gatheringdevice position outside of tire 14. Monitoring package 34 also includesconnecting elements 36 that are configured to mate with connectingelements 32 to form a direct electrical connection between monitoringpackage 34 and antenna 30.

[0032] In accordance with one of the objectives of the presentinvention, monitoring package 34 is encapsulated with an encapsulationmaterial 40 directly to attachment patch 20 such that encapsulationmaterial 40 is chemically and/or physically bonded to attachment patch20. In one embodiment of the invention, a frame 42 is fabricated andattached to first side 24 of attachment patch 20 by an adhesive 44 byapplying adhesive 44 around frame 42 and ensuring a continuous bead ofadhesive 44 around the perimeter. In one embodiment, a copper facedboard having a thickness of 0.0345 inches is used to fabricate frame 42by soldering the ends of four pieces together to form frame 42. Anotherpreferred material for forming frame 42 is glass-filled epoxy. In otherembodiments, substantially any material may be used for frame 42 thatwill not interfere with a radio frequency signal if frame 42 remainsconnected to encapsulated monitoring device 22 as depicted in FIG. 5 andwill not melt at the relatively high encapsulation or pottingtemperature. This temperature is typically 95-125 degrees Celsius.

[0033] In another embodiment of the invention, frame 42 is held againstfirst side 24 of attachment patch 20 by applying pressure as indicatedby the numeral 46 against frame 42. Pressure 46 maintains the correctposition of frame 42 and prevents encapsulation material 40 from leakingout from between frame 42 and attachment patch 20.

[0034] Frame 42 is positioned on attachment patch 20 such thatconnecting elements 32 are disposed within frame 42. The position ofconnecting elements 32 with respect to frame 42 is referred to as theconnection location. It is an important aspect of the present inventionto provide strength around the connection location so that theconnections between monitoring package 34 and antenna 30 do not becomeloose with extended use of patch 10.

[0035] Depending on the material used to fabricate frame 42, frame 42may need to be sandblasted and degreased with solvent to clean thesurface prior to performing the encapsulation steps of the presentinvention. For instance, the copper-faced board discussed above ispreferably sandblasted and solvent washed to clean the surface. Inaddition, first side 24 of attachment patch 20 is preferably cleaned andprimed with a 3% 1, 3, 5-Trichloro-s-triazinetrione(Trichloroisocyanuric acid) (TCTT) solutions in butyl actetate. Side 24was then wiped with a piece of Rymplecloth to remove the excess solventand surface dirt. Patch 20 was then allowed to dry thoroughly. Adhesive44 used around frame 42 is preferably FUSOR®D 320 (five parts byweight)/310 B (two parts by weight). FUSOR® is available from LordCorporation. Adhesive 44 is then cured in an oven at 80 degrees Celsiusfor thirty minutes.

[0036] Various other types of adhesives, frame materials, and surfacepreparations may be used without departing from the scope of the presentinvention. The specific materials and times described above are merelyfor the purpose of providing an exemplary embodiment of the inventionand the best mode now known for performing the invention.

[0037] Monitoring package 34 is then positioned within frame 42 so thatit is suspended within frame 42 adjacent first side 24. A chimney 48 maybe attached to a sensor (such as a pressure sensor or a temperaturesensor) on monitoring package 34 so that it may communicate with theatmosphere surrounding encapsulated monitoring device 22 afterencapsulation material 40 is cured. Chimney 48 provides an air passage50 to monitoring package 34.

[0038] After monitoring package 34 is positioned adjacent first side 24and within frame 42, encapsulation material 40 is introduced insideframe 42 to substantially surround monitoring package 34 and to fillsubstantially all voids around monitoring package 34 as depicted in FIG.5. In the preferred embodiment of the present invention, encapsulationmaterial 40 is a formulation including 100 gm STYCAST® 2651; 7 gmCatalyst 9; and 3 drops defoamer 88. In another embodiment of theinvention, encapsulation material 40 is a formulation including 110 gmSTYCAST® 2651; 10 gm Phenyl Gycidyl Ether; 9.4 gm Catalyst 9; and 6drops of defoamer 88. These materials were mixed together at roomtemperature until thoroughly mixed. The formulation was degassed untilfoaming subsided. The formulation was then poured into frame 42 andallowed to cure in an oven at 55 degrees Celsius for thirty minutes. Itwas then post-cured at 80 degrees Celsius for thirty minutes. Thisprocess results in a strong encapsulated monitoring device 22 directlybonded to attachment patch 20. Frame 42 may be left in position asdepicted in FIG. 5 or removed as depicted in FIG. 6.

[0039] Various other encapsulation materials 40 will also function withthe present invention. For instance, a variety of epoxies and urethanesthat are pourable and cure to a rigid tough material having a highmodulus of elasticity may be used. It is desired that encapsulationmaterial 40 having a Young's modulus of at least 30,000 psi and which iscapable of being molded around electronic monitoring package 34.Preferably, encapsulation material 40 will have a Young's modulus atleast 100,000 psi.

[0040] STYCAST®2651 is the preferred encapsulation material.Alternatively, high melting point polyurethanes and/or polyureas may beutilized. The polyurethanes are derived from polysiocyanates whichgenerally have the formula R(NO)_(n) where n is an integer of 2, 3 or 4with approximately 2 being preferred. The “n” may, however, vary andoften is not an integer because combinations of various polysiocyanatescan be utilized. R is an aliphatic having from about 2 to about 20carbon atoms or preferably an aromatic including an alkyl substitutedaromatic having from about 6 to about 20 carbon atoms with from about 6to about 15 carbon atoms being desired, or combinations thereof.Examples of suitable polysiocyanates include 1,6-diisocyanto hexane;2,2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate; p- andm-tetramethyl xylene diisocyanate; dicyclohexylmethane-4,4′-diisocyanate(Hydrogenated MDI); 4,4-methylene diphenyl isocyanate (MDI); p- andm-phenylene diisocyanate; 2,4-and/or 2,6-toluene diisocyanate (TDI);durene-1,4-diisocyanate; isophorone diisocyanate and isopropylenebis-(p-phenyl isocyanate). TDI is desirably utilized. The variousdiphenylmethane diisocyanates (MDI) and mixtures of MDI with polymericMDI having an average isocyanate functionality of from about 2 to about3.2 are preferred.

[0041] The preparation of the polyurethanes and/or polyureas are wellknown to the art and to the literature. For example, a short chainoligomer or polymer derived from polyester or polyether polyolsgenerally having a molecular weight of from about 55 to about 1,000 andpreferably from about 6 to about 200 are reacted with the above-noteddiisocyanates to form a urethane prepolymer. Similarly, a short chaindiamine can be utilized and reacted with the above-noted diisocyanatesto form a urea prepolymer. Aromatic diisocyanates are generally utilizedto yield high melting point urethane or urea prepolymers which alsogenerally have a high modulus of elasticity. The resulting prepolymer issubsequently reacted with diols, diamine, diacids, or amino alcohols,and the like to cure the same and form a polyurethane or polyurea.Alternatively, the polyurethanes and/or polyureas are formed by reactingan existing prepolymer with the above-noted curing or chain extendingagents.

[0042] The equivalent ratio of isocyanate groups (NCO) reacted with thehydroxyl groups (OH) or amine groups (NH₂) of the short chain compoundis generally from about 0.90 to about 1.10, desirably from about 0.95 toabout 1.05, and preferably from about 0.98 to about 1.02.

[0043] In general, thermoset epoxy resins are preferred. The epoxy resinor polymer is generally formed by the reaction of bisphenol A andepichlorohydrin. The preparation of epoxy resins is well known to theliterature and to the art. Generally, epichlorohydrin is reacted with avariety of hydroxy, carboxy, or amino compounds to form monomers withtwo or more epoxied groups, and these monomers are then used in thereaction with bisphenol A. Examples of such compounds are the diglycidylderivative of cyclohexane-1,2-dicarboxylic acid, the triglycidylderivates of p-aminophenol and cyanuric acid, and the polyglycidylderivative of phenolic prepolymers. Epoxidized diolefins can also beemployed. Various co-reactants can be utilized to cure epoxy resinseither through the epoxied or hydroxyl groups. Polyamines such asprimary or secondary amines are a common curing agent such as aliphaticamines having a total of from about 2 to about 18 carbon atoms anddesirably from about 4 to about 8 carbon atoms. Suitable compoundsinclude diethylene triamine, triethylene tetraamine, tetraethylenepentaamine, 4,4′-diaminodiphenylmethane, and polyaminoamides. Acombination of diethylene triamine and tetraethylene pentaamine is oftendesired. Aromatic amines can also be utilized such as those having atotal of from 6 to 20 carbon atoms such as meta or paraphenylene diamineand the like. Other curing agents including polythiols, dicyandiamide(cyanoguanidine), diisocyanates, and phenolic prepolymers. Curing ofepoxy resins can also be achieved by ring opening polymerization of theepoxied groups using either Lewis acids or Lewis bases.

[0044] Accordingly, the improved attachment patch for mounting anelectronic monitoring device to the inside of a pneumatic tire apparatusis simplified, provides an effective, safe, inexpensive, and efficientdevice which achieves all the enumerated objectives, provides foreliminating difficulties encountered with prior devices, and solvesproblems and obtains new results in the art.

[0045] In the foregoing description, certain terms have been used forbrevity, clearness, and understanding; but no unnecessary limitationsare to be implied therefrom beyond the requirement of the prior art,because such terms are used for descriptive purposes and are intended tobe broadly construed.

[0046] Moreover, the description and illustration of the invention is byway of example, and the scope of the invention is not limited to theexact details shown or described.

[0047] Having now described the features, discoveries, and principles ofthe invention, the manner in which the attachment patch for mounting anelectronic monitoring device to the inside of a pneumatic tire isconstructed and used, the characteristics of the construction, and theadvantageous new and useful results obtained; the new and usefulstructures, devices, elements, arrangements, parts, and combinations areset forth in the appended claims.

1. A method of forming a patch to mount an electronic monitoring deviceinside a pneumatic tire, the method comprising the steps of: (a)providing an attachment patch having a first surface and a secondsurface; (b) providing an electronic monitoring device adjacent thefirst surface of the attachment patch; and (c) encapsulating theelectronic monitoring device directly to the first surface of theattachment patch with an encapsulation material.
 2. The method of claim1, further comprising the steps of: attaching an antenna to theattachment patch; connecting the electronic monitoring device to theantenna at a connection location; and covering the connection locationduring step (c).
 3. The method of claim 2, further comprising the stepsof: providing connectors that protrude out from the attachment patch;plugging the monitoring device into the connectors; and surrounding theconnectors with encapsulation material during step (c).
 4. The method ofclaim 1, wherein step (c) includes the steps of providing a framesurrounding the electronic monitoring device and filling the frame withthe encapsulation material.
 5. The method of claim 4, further comprisingthe step of providing an encapsulation material that primarily includesSTYCAST®
 2651. 6. The method of claim 4, further comprising the step ofproviding an encapsulation material that is one of a polyurethane and apolyureaurethane.
 7. The method of claim 4, further comprising the stepof providing an encapsulation material that is an epoxy.
 8. The methodof claim 4, further comprising the step of providing an encapsulationmaterial that has a high modulus of elasticity when it is cured.
 9. Themethod of claim 4, further comprising the step of curing theencapsulation material.
 10. The method of claim 9, further comprisingthe step of curing the encapsulation material at 80 degrees Celsius forthirty minutes.
 11. The method of claim 4, further comprising the stepof pressing the frame against the patch when filling the frame with theencapsulation material.
 12. The method of claim 4, further comprisingthe step of using an adhesive to hold the frame on the patch.
 13. Themethod of claim 4, wherein the step of filling the frame with anencapsulation material includes the step of pouring the encapsulationmaterial into the frame around the electronic monitoring device.
 14. Themethod of claim 13, further comprising the step of providing theencapsulation material in a flowable form.
 15. The method of claim 1,wherein step (c) includes the steps of pouring the encapsulationmaterial in a flowable form directly onto the patch.
 16. The method ofclaim 15, further comprising the step of curing the flowableencapsulation material while the material is in direct contact with thepatch.